Base L2 Development

Base is Coinbase's L2 built on Optimism's OP Stack. It shares Ethereum security, uses ETH as gas, and settles to L1. If you can deploy to Ethereum, you can deploy to Base with zero code changes — just point at a different RPC.

What You Probably Got Wrong

• Base is NOT a separate EVM — It is an OP Stack rollup. Same opcodes, same Solidity compiler, same tooling. There is nothing "Base-specific" about contract development. If your contract works on Ethereum or Optimism, it works on Base.
• Gas has two components — L2 execution gas (cheap, ~0.001 gwei base fee) plus L1 data fee (variable, depends on Ethereum blob fees). The L1 data fee is the dominant cost for most transactions. After EIP-4844 (Dencun), L1 data costs dropped ~100x.
• msg.sender works differently with Smart Wallet — Coinbase Smart Wallet is a smart contract account (ERC-4337). msg.sender is the smart wallet address, not the EOA. If your contract checks tx.origin == msg.sender to block contracts, it will block Smart Wallet users.
• OnchainKit is NOT a wallet library — It is a React component library for building Base-native UIs. It handles identity resolution, transaction submission, token swaps, and Farcaster frames. You still need wagmi/viem for the underlying wallet connection.
• Paymaster does NOT mean free transactions — A paymaster sponsors gas on behalf of users. Someone still pays. You configure a Coinbase Developer Platform paymaster policy that defines which contracts and methods are sponsored, with spend limits.
• Block time is 2 seconds — Not 12 seconds like Ethereum L1. Plan your polling and confirmation logic accordingly.
• Basescan and Blockscout are both available — Basescan (Etherscan-based) is the primary explorer. Blockscout is the alternative. Contract verification works on both but uses different APIs.

Quick Start